[clang] [X86_32] Teach X86_32 va_arg to ignore empty structs. (PR #86075)

[Longsheng Mou via cfe-commits]

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@@ -1069,6 +1069,10 @@ Address X86_32ABIInfo::EmitVAArg(CodeGenFunction &CGF,
 
   auto TypeInfo = getContext().getTypeInfoInChars(Ty);
 
+  // Empty records are ignored for parameter passing purposes on non-Windows.
+  if (!IsWin32StructABI && isEmptyRecord(getContext(), Ty, true))
+    return CGF.CreateMemTemp(Ty);
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CoTinker wrote:

classifyArgumentType in X86_32 need CCState parameter, but we can not get it in this scope, because the CCState is temporarily calculated in X86_32ABIInfo::computeInfo.

https://github.com/llvm/llvm-project/pull/86075